<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .wrap {
            display:flex;
            flex-direction: row;
            width:375px;
            height:300px;
            justify-content: space-between;
            flex-wrap:wrap;
        }

        .item {
            width:100px;
            height:100px;
            background:pink;
        }
    </style>
</head>
<body>
    <div class="wrap">
        <div class="item">1</div>
        <div class="item">2</div>
        <div class="item">3</div>
        <div class="item">4</div>
        <div class="item">5</div>
        <div class="item">6</div>
    </div>  
</body>
</html>